The vehicle-mounted plow used for snow and light earth plowing is typically configured with a forwardly oriented concave longitudinally curved plow with its lower surface contacting the surface to which it is applied with an acute angle significantly less than 90.degree.. In tight plowing locations such as in front of a locked garage door or in a dead end or a corner, it is desirable to move the snow or earth while travelling in a reverse direction to back drag snow or soil without reversing the direction of the entire vehicle. It is also desirable to completely remove the snow from the surface, leaving no residual layer on the surface, which through succeeding accumulations, build up forming icy ridges, uneven surfaces, or other dangerous situations. However, the low angle with which the plow blade meets the surface in the forward direction to separate and lift the snow or gravel from the surface now causes the plow to glide over the surface when moving in the reverse direction, displacing little of the snow or gravel.
Smaller plow blades used for residential or light plowing typically incorporate a lower portion forming a minor blade, typically called a `trip edge` (or base angle), interposed between the main portion of the plow and the surface to be plowed, wherein the minor blade is typically resiliently pivoted on the lower portion of the main blade to swing rearward in the event of striking a rock or other relatively unmovable protrusion while moving in the forward direction, thus preventing the entire force of the plow vehicle to bear on the plow blade at that point. Thus, the normal operating position of the lower portion is in the forward position, moving rearward only in response to the occasional obstructions on the surface and thus being relatively ineffective in moving snow or soil behind the trip edge.